In this thesis, the applications of the recurrence quantification analysis in metal cutting
operation in a lathe, with specific objective to detect tool wear and chatter, are
presented.This study is based on the discovery that process dynamics in a lathe is low dimensional
chaotic. It implies that the machine dynamics is controllable using principles of chaos
theory. This understanding is to revolutionize the feature extraction methodologies
used in condition monitoring systems as conventional linear methods or models are
incapable of capturing the critical and strange behaviors associated with the metal
cutting process.As sensor based approaches provide an automated and cost effective way to monitor
and control, an efficient feature extraction methodology based on nonlinear time series
analysis is much more demanding. The task here is more complex when the information
has to be deduced solely from sensor signals since traditional methods do not address
the issue of how to treat noise present in real-world processes and its non-stationarity.
In an effort to get over these two issues to the maximum possible, this thesis adopts the
recurrence quantification analysis methodology in the study since this feature extraction
technique is found to be robust against noise and stationarity in the signals.The work consists of two different sets of experiments in a lathe; set-I and set-2. The
experiment, set-I, study the influence of tool wear on the RQA variables whereas the set-2 is carried out to identify the sensitive RQA variables to machine tool chatter
followed by its validation in actual cutting. To obtain the bounds of the spectrum of the
significant RQA variable values, in set-i, a fresh tool and a worn tool are used for
cutting. The first part of the set-2 experiments uses a stepped shaft in order to create
chatter at a known location. And the second part uses a conical section having a uniform
taper along the axis for creating chatter to onset at some distance from the smaller end
by gradually increasing the depth of cut while keeping the spindle speed and feed rate
constant.The study concludes by revealing the dependence of certain RQA variables; percent
determinism, percent recurrence and entropy, to tool wear and chatter unambiguously.
The performances of the results establish this methodology to be viable for detection of
tool wear and chatter in metal cutting operation in a lathe. The key reason is that the
dynamics of the system under study have been nonlinear and the recurrence
quantification analysis can characterize them adequately.This work establishes that principles and practice of machining can be considerably
benefited and advanced from using nonlinear dynamics and chaos theory.

One major component of power system operation is generation
scheduling. The objective of the work is to develop efficient control strategies
to the power scheduling problems through Reinforcement Learning approaches.
The three important active power scheduling problems are Unit Commitment,
Economic Dispatch and Automatic Generation Control. Numerical solution
methods proposed for solution of power scheduling are insufficient in handling
large and complex systems. Soft Computing methods like Simulated Annealing,
Evolutionary Programming etc., are efficient in handling complex cost
functions, but find limitation in handling stochastic data existing in a practical
system. Also the learning steps are to be repeated for each load demand which
increases the computation time.Reinforcement Learning (RL) is a method of learning through
interactions with environment. The main advantage of this approach is it does
not require a precise mathematical formulation. It can learn either by interacting
with the environment or interacting with a simulation model. Several
optimization and control problems have been solved through Reinforcement
Learning approach. The application of Reinforcement Learning in the field of
Power system has been a few. The objective is to introduce and extend
Reinforcement Learning approaches for the active power scheduling problems
in an implementable manner. The main objectives can be enumerated as:(i) Evolve Reinforcement Learning based solutions to the Unit
Commitment Problem.(ii) Find suitable solution strategies through Reinforcement Learning
approach for Economic Dispatch.
(iii) Extend the Reinforcement Learning solution to Automatic Generation
Control with a different perspective.
(iv) Check the suitability of the scheduling solutions to one of the existing
power systems.First part of the thesis is concerned with the Reinforcement Learning
approach to Unit Commitment problem. Unit Commitment Problem is
formulated as a multi stage decision process. Q learning solution is developed
to obtain the optimwn commitment schedule. Method of state aggregation is
used to formulate an efficient solution considering the minimwn up time I down
time constraints. The performance of the algorithms are evaluated for different
systems and compared with other stochastic methods like Genetic Algorithm.Second stage of the work is concerned with solving Economic Dispatch
problem. A simple and straight forward decision making strategy is first
proposed in the Learning Automata algorithm. Then to solve the scheduling
task of systems with large number of generating units, the problem is
formulated as a multi stage decision making task. The solution obtained is
extended in order to incorporate the transmission losses in the system. To make
the Reinforcement Learning solution more efficient and to handle continuous
state space, a fimction approximation strategy is proposed. The performance of
the developed algorithms are tested for several standard test cases. Proposed
method is compared with other recent methods like Partition Approach
Algorithm, Simulated Annealing etc.As the final step of implementing the active power control loops in
power system, Automatic Generation Control is also taken into consideration.Reinforcement Learning has already been applied to solve Automatic
Generation Control loop. The RL solution is extended to take up the approach
of common frequency for all the interconnected areas, more similar to practical
systems. Performance of the RL controller is also compared with that of the
conventional integral controller.In order to prove the suitability of the proposed methods to practical
systems, second plant ofNeyveli Thennal Power Station (NTPS IT) is taken for
case study. The perfonnance of the Reinforcement Learning solution is found to
be better than the other existing methods, which provide the promising step
towards RL based control schemes for practical power industry.Reinforcement Learning is applied to solve the scheduling problems in
the power industry and found to give satisfactory perfonnance. Proposed
solution provides a scope for getting more profit as the economic schedule is
obtained instantaneously. Since Reinforcement Learning method can take the
stochastic cost data obtained time to time from a plant, it gives an
implementable method. As a further step, with suitable methods to interface
with on line data, economic scheduling can be achieved instantaneously in a
generation control center. Also power scheduling of systems with different
sources such as hydro, thermal etc. can be looked into and Reinforcement
Learning solutions can be achieved.

Software systems are progressively being deployed in many facets
of human life. The implication of the failure of such systems, has an
assorted impact on its customers. The fundamental aspect that supports a
software system, is focus on quality. Reliability describes the ability of
the system to function under specified environment for a specified
period of time and is used to objectively measure the quality. Evaluation
of reliability of a computing system involves computation of hardware
and software reliability. Most of the earlier works were given focus on
software reliability with no consideration for hardware parts or vice
versa. However, a complete estimation of reliability of a computing
system requires these two elements to be considered together, and thus
demands a combined approach. The present work focuses on this and
presents a model for evaluating the reliability of a computing system.
The method involves identifying the failure data for hardware
components, software components and building a model based on it, to
predict the reliability. To develop such a model, focus is given to the
systems based on Open Source Software, since there is an increasing
trend towards its use and only a few studies were reported on the
modeling and measurement of the reliability of such products. The
present work includes a thorough study on the role of Free and Open
Source Software, evaluation of reliability growth models, and is trying
to present an integrated model for the prediction of reliability of a
computational system. The developed model has been compared with
existing models and its usefulness of is being discussed.

The service quality of any sector has two major aspects namely technical and functional. Technical quality can be attained by maintaining technical specification as decided by the organization. Functional quality refers to the manner which service is delivered to customer which can be assessed by the customer feed backs. A field survey was conducted based on the management tool SERVQUAL, by designing 28 constructs under 7 dimensions of service quality. Stratified sampling techniques were used to get 336 valid responses and the gap scores of expectations and perceptions are analyzed using
statistical techniques to identify the weakest dimension. To assess the technical aspects of availability six months live outage data of base transceiver were collected. The statistical and exploratory techniques were used to model the network performance. The failure patterns have been modeled in competing risk models and probability distribution of service outage and restorations were parameterized. Since the availability of network is a function of the reliability and maintainability of the network elements, any service provider who wishes to keep up their service level agreements on availability should be aware of the variability of these elements and its effects on interactions. The availability variations were studied by designing a discrete time event simulation model with probabilistic input parameters. The probabilistic distribution parameters arrived from live data analysis was used to design experiments to define the availability domain of the network under consideration. The availability domain can be used as a reference for planning and implementing maintenance activities. A new metric is proposed which incorporates a consistency index along with key service parameters that can be used to compare the performance of different service providers. The developed tool can be used for reliability analysis of mobile communication systems and assumes greater significance in the wake of mobile portability facility. It is also possible to have a relative measure of the effectiveness of different service providers.

Files in this item: 1

Meril, George
Beena, K S(Cochin University of Science and Technology, December 17, 2014)

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Abstract:

Leachate from an untreated landfill or landfill with damaged liners
will cause the pollution of soil and ground water. Here an attempt was made
to generate knowledge on concentrations of all relevant pollutants in soil
due to municipal solid waste landfill leachate and its migration through soil
and also to study the effect of leachate on the engineering properties of soil.
To identify the pollutants in soil due to the leachate generated from
municipal solid waste landfill site, a case study on an unlined municipal
solid waste landfill at Kalamassery has been done. Soil samples as well as
water samples were collected from the site and analysed to identify the
pollutants and its effect on soil characteristics. The major chemicals in the
soil were identified as Ammonia, Chloride, Nitrate, Iron, Nickel,
Chromium, Cadmium etc.. Engineering properties of field soil samples
show that the chemicals from the leachate of landfill may have effect on the
engineering properties of soil.
Laboratory experiments were formulated to model the field around an
unlined MSW landfill using two different soils subjected to a synthetic
leachate. The Maximum change in chemical concentration and engineering
property was observed on soil samples at a radial distance of 0.2 m and at a
depth of 0.3 m. The pollutant (chemicals) transport pattern through the
soil was also studied using synthetic leachate. To establish the effect of
pollutants (chemicals) on engineering properties of soil, experiments were
conducted on two types soils treated with the synthetic chemicals at four
different concentrations. Analyses were conducted after maturing periods of
7, 50, 100 and 150 days. Test soils treated with maximum chemical
concentration and matured for 150 days were showing major change in the
properties.
To visualize the flow of pollutants through soil in a broader sense, the
transportation of pollutants through soil was modeled using software ‘Visual
MODFLOW’. The actual field data collected for the case study was used to
calibrate the modelling and thus simulated the flow pattern of the pollutants
through soil around Kalamassery municipal solid waste landfill for an extent
of 4 km2. Flow was analysed for a time span of 30 years in which the
landfill was closed after 20 years. The concentration of leachate beneath the
landfill was observed to be reduced considerably within one year after
closure of landfill and within 8 years, it gets lowered to a negligible level.
As an environmensstal management measure to control the pollution
through leachate, permeable reactive barriers are used as an emerging
technology. Here the suitability of locally available materials like coir pith,
rice husk and sugar cane bagasse were investigated as reactive media in
permeable reactive barrier. The test results illustrates that, among these, coir
pith was showing better performance with maximum percentage reduction
in concentration of the filtrate. All these three agricultural wastes can be
effectively utilized as a reactive material.
This research establishes the influence of leachate of municipal solid
waste landfill on the engineering properties of soil. The factors such as type
of the soil, composition of leachate, infiltration rate, aquifers, ground water
table etc., will have a major role on the area of influence zone of the
pollutants in a landfill. Software models of the landfill area can be used to
predict the extent and the time span of pollution of a landfill, by inputting
the accurate field parameters and leachate characteristics. The present study
throws light on the role of agro waste materials on the reduction of the
pollution in leachate and thus prevents the groundwater and soil from
contamination

The present study aimed at critically looking at the current practice of the
installation of compacted clay liner using bentonite enhanced sand (BES).
The application of bentonite is currently the most accepted practice for
lining purposes. The ideal bentonite sand combination, which satisfies the liner
requirements is 20% bentonite and 80% sand, was selected as one of the liner
materials for the investigation of development of desiccation cracks. Locally
available sundried marine clay and its combination with bentonite were also
included in the study. The desiccation tests on liner materials were conducted for
wet/dry cycles to simulate the seasonal variations. Digital image processing
techniques were used to measure the crack intensity factor (CIF), a
useful and effective parameter for quantification of desiccation cracking.
The repeatability of the tests could be well established, as the variation in CIF values
of identical samples had a very narrow range of 0 to 2%. The studies on the
development of desiccation cracks showed that the CIF of bentonite enhanced
sand mixture (BES) was 18.09%, 39.75% and 21.22% for the
first, second and third cycles respectively, while it was only 9.83%, 7.52% and
4.58% respectively for sun dried marine clay (SMC). Thus the locally available,
alternate liner material suggested, viz SMC, is far superior to BES, when
subjected to alternate wet/dry cycles. Further, the improvement of these liner materials when amended with randomly distributed fibre reinforcements was also investigated. Three types of
fibres ,namely nylon fibre, polypropylene monofilament and polypropylene fibre
mesh were used for the study of fibre amended BES and SMC.The influence of
these amendments on the properties of the above liner materials is also studied.
The results showed that there is definite improvement in the properties of the liner
materials when it is reinforced with discrete random fibres. The study also proved
that the desiccation cracks could be controlled with the help of fibre
reinforcement.

Investigations on the fracture behaviour of polymer blends is the topic of
this thesis. The blends selected are PP/HDPE and PS/HIPS. PP/HDPE blend is
chosen due to its commercial importance and PS/HIPS blend is selected to study
the transition from brittle fracture to ductile fracture.PP/HDPE blends were prepared at different compositions by melt blending
at 180°C and fracture failure process was investigated by conducting notch
sensitivity test and tensile test at different strain rates. The effects of two types of
modifiers (particulate and elastomer) on the fracture behaviour and notch
sensitivity of PP/HDPE blends were studied. The modifiers used are calcium
carbonate, a hard particulate filler commonly used in plastics and Ethylene
Propylene Diene Monomer (EPDM). They were added in 2%, 4% and 6% by
weight of the blends.The study shows that the mechanical properties of PP/HDPE blends can be
optimized by selecting proper blend compositions. The selected modifiers are
found to alter and improve the fracture behaviour and notch sensitivity of the
blends. Particulate fillers like calcium carbonate can be used for making the
mechanical behaviour more stable at the various blend compositions. The
resistance to notch sensitivity of the blends is found to be marginally lower in the
presence of calcium carbonate. The elastomeric modifier EPDM produces a better
stability of the mechanical behaviour. A low concentration of EPDM is sufficient
to effect such a change. EPDM significantly improves the resistance to notch
sensitivity of the blends. The study shows that judicious selection of modifiers can
improve the fracture behaviour and notch sensitivity of PP/HDPE blends and help
these materials to be used for critical applications.For investigating the transition in fracture behaviour and failure modes,
PS/HIPS blends were selected. The blends were prepared by melt mixing followed
by injection moulding to prepare the specimens for conducting tensile, impact and
flexure tests. These tests were used to simulate the various conditions which
promote failure.The tensile behaviour of unnotched and notched PS/HIPS blend samples
were evaluated at slow speeds. Tensile strengths and moduli were found to
increase at the higher testing speed for all the blend combinations whereas
maximum strain at break was found to decrease. For a particular speed of testing,
the tensile strength and modulus show only a very slight decrease as HIPS content
is increased up to about 40%. However, there is a drastic decrease on increasing
the HIPS content thereafter.The maximum strain at break shows only a very slight change up to about
40% HIPS content and thereafter shows a remarkable increase. The notched
specimens also follow a comparable trend even though the notch sensitivity is seen
high for PS rich blends containing up to 40% HIPS. The notch sensitivity
marginally decreases with increase in HIPS content. At the same time, it is found
to increase with the increase in strain rate. It is observed that blends containing
more than 40% HIPS fail in ductile mode.The impact characteristics of PSIHIPS blends studied were impact strength,
the energy absorbed by the test specimen and impact toughness. Remarkable
increase in impact strength is observed as HIPS content in the blend exceeds 40%.
The energy absorbed by the test specimens and the impact toughness also show a
comparable trend.Flexural testing which helps to characterize the load bearing capacity was
conducted on PS/HIPS blend samples at the two different testing speeds of
5mmlmin and 10 mm/min. The flexural strength increases with increase in testing
speed for all the blend compositions. At both the speeds, remarkable reduction in
flexural strength is observed as HIPS content in the blend exceeds 40%. The
flexural strain and flexural energy absorbed by the specimens are found to increase
with increase in HIPS content. At both the testing speeds, brittle fracture is
observed for PS rich blends whereas HIPS rich blends show ductile mode of
failure.Photoelastic investigations were conducted on PS/HIPS blend samples to
analyze their failure modes. A plane polariscope with a broad source of light was
utilized for the study. The coloured isochromatic fringes formed indicate the
presence of residual stress concentration in the blend samples. The coverage made
by the fringes on the test specimens varies with the blend composition and it
shows a reducing trend with the increase in HIPS content. This indicates that the
presence of residual stress is a contributing factor leading to brittle fracture in PS
rich blends and this tendency gradually falls with increase in HIPS content and
leads to their ductile mode of failure.

The present study focused on the quality of rainwater at various land use
locations and its variations on interaction with various domestic rainwater
harvesting systems.Sampling sites were selected based upon the land use
pattern of the locations and were classified as rural, urban, industrial and
sub urban. Rainwater samples were collected from the south west monsoon of
May 2007 to north east monsoon of October 2008, from four sampling sites namely Kothamangalam, Emakulam, Eloor and Kalamassery, in Ernakulam
district of the State of Kerala, which characterized typical rural, urban,
industrial and suburban locations respectively. Rain water samples at various
stages of harvesting were also collected. The samples were analyzed according
to standard procedures and their physico-chemical and microbiological
parameters were determined. The variations of the chemical composition of the rainwater collected
were studied using statistical methods. It was observed that 17.5%, 30%,
45.8% and 12.1% of rainwater samples collected at rural, urban, industrial and
suburban locations respectively had pH less than 5.6, which is considered as
the pH of cloud water at equilibrium with atmospheric CO,.Nearly 46% of the
rainwater samples were in acidic range in the industrial location while it was
only 17% in the rural location. Multivariate statistical analysls was done using
Principal Component Analysis, and the sources that inf1uence the composition
of rainwater at each locations were identified .which clearly indicated that the
quality of rain water is site specific and represents the atmospheric
characteristics of the free fall The quality of harvested rainwater showed significant variations at
different stages of harvesting due to deposition of dust from the roof
catchment surface, leaching of cement constituents etc. Except the micro
biological quality, the harvested rainwater satisfied the Indian Standard guide
lines for drinking water. Studies conducted on the leaching of cement
constituents in water concluded that tanks made with ordinary portland cement
and portland pozzolana cement could be safely used for storage of rain water.

This thesis deals with the use of simulation as a problem-solving tool to solve a
few logistic system related problems. More specifically it relates to studies on
transport terminals. Transport terminals are key elements in the supply chains of
industrial systems. One of the problems related to use of simulation is that of the
multiplicity of models needed to study different problems. There is a need for
development of methodologies related to conceptual modelling which will help
reduce the number of models needed. Three different logistic terminal systems
Viz. a railway yard, container terminal of apart and airport terminal were selected
as cases for this study. The standard methodology for simulation development
consisting of system study and data collection, conceptual model design, detailed
model design and development, model verification and validation,
experimentation, and analysis of results, reporting of finding were carried out.
We found that models could be classified into tightly pre-scheduled, moderately
pre-scheduled and unscheduled systems. Three types simulation models( called
TYPE 1, TYPE 2 and TYPE 3) of various terminal operations were developed in
the simulation package Extend. All models were of the type discrete-event
simulation. Simulation models were successfully used to help solve strategic,
tactical and operational problems related to three important logistic terminals as
set in our objectives. From the point of contribution to conceptual modelling we
have demonstrated that clubbing problems into operational, tactical and strategic
and matching them with tightly pre-scheduled, moderately pre-scheduled and
unscheduled systems is a good workable approach which reduces the number of
models needed to study different terminal related problems.

Files in this item: 1

Vinodkumar,M N; Dr.Bhasi, M(Cochin University of Science and Technology, June , 2005)

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Abstract:

In the twentieth century, as technology grew with it. This resulted in collective efforts and thinking in the direction of controlling work related hazards and accidents. Thus, safety management developed and became an important part of industrial management. While considerable research has been reported on the topic of safety management in industries from various parts of the world, there is scarcity of literature from India. It is logical to think that a clear understanding of the critical safety management practices and their relationships with accident rates and management system certifications would help in the development and implementation of safety management systems.
In the first phase of research, a set of six critical safety management practices has been identified based on a thorough review of the prescriptive, practitioner, conceptual and empirical literature. An instrument for measuring the level of practice of these safety conduction a survey using questionnaire in chemical/process industry. The instrument has been empirically validated using Confirmatory Factor Analysis (CFA) approach. As the second step. Predictive validity of safety management practices and the relationship between safety management practices and self-reported accident rates and management system certifications have been investigated using ANOVA. Results of the ANOVA tests show that there is significant difference in the identified safety management practices and the determinants of safety performance have been investigated using Multiple Regression Analysis. The inter-relationships between safety management practices, determinants of safety performance and components of safety performance have been investigated with the help of structural equation modeling. Further investigations into engineering and construction industries reveal that safety climate factors are not stable across industries. However, some factors are found to be common in industries irrespective of the type of industry.
This study identifies the critical safety management practices in major accident hazard chemical/process industry from the perspective of employees and the findings empirically support the necessity for obtaining safety specific management system certifications

Files in this item: 1

Benny, Mathews Abraham; Dr.Babu,Jose T(Cochin University Of Science And Technology, November 23, 1993)

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Abstract:

With the advent of urbanisation and consequent
search for more and more habitable land, it was imperative
that the large tracts of marine clays, considered inhabitable
earlier, had to be reclaimed and developed. These marine
clays, wellknown for its high compressibility and poor shear
strength, posed numerous problems to the builders and Cochin
was no exception. It is only less than a decade since active
research work was initiated on marine clays in general and
Cochin marine clays in particular. Eventhough some systematic
studies are available on compressibility characteristics,
attempts to study the shear strength aspects and development
of techniques to improve it have been very limited. This work
is an investigation on the consolidation and shear strength
characteristics of Cochin marine clays including methods to
improve the same

Soft clays known for their high compressibility, low stiffness and low shear strength are always associated with large settlement. In place soil treatment using calcium-based stabilizers like lime and cement is a feasible solution to readdress strength deficiencies and problematic shrink/swell behaviour of unstable subgrade soils. Out of these, lime has been proved unambiguously as the most effective and economical stabilising agent for marine clays. Lime stabilisation creates long-term chemical changes in unstable clay soils to create strong, but flexible, permanent structural layers in foundations and other pavement systems. Even though calcium-based stabilizers can improve engineering properties of soft clays, problems can arise when they are used in soils rich in sulphates. It is possible for marine clays to be enriched with sulphates, either by nature or due to the discharge of nearby industrial wastes containing sulphates. The presence of sulphates is reported to adversely affect the cation exchange and pozzolanic reactions of cement and lime treated soil systems. The anions of sulphates may combine with the available calcium and alumina, and form insoluble ettringite in the soil system. Literature on sulphate attack in lime treated marine clays reports that formation of ettringite in lime-sodium sulphate-clay system is capable of adversely affecting the engineering behavior of marine clays.
Only very few studies have been conducted on soft marine clays found along the coastal belt of Kerala and that too, is limited to Cochin marine clays. The studies conducted also have the limitation that the strength behaviour of lime stabilised clay was investigated only for one year. Practically no data pertaining to long term adverse effects likely to be brought about by sulphates on the strength and compressibility characteristics of Cochin marine clays is available. The overriding goal of this investigation was thus to examine the effectiveness of lime stabilisation in Cochin marine clays under varying sulphate contents. The study aims to reveal the changes brought about by varying sulphate contents on both physical and engineering properties of these clays stabilised by lime and the results for various curing periods up to two years is presented in this thesis. Quite often the load causing an unacceptable settlement may be less than the load required to cause shear failure and therefore attempt has been made in this research to highlight sulphate induced changes in both the compressibility and strength characteristics of lime treated Cochin marine clays. The study also aimed at comparing the available IS methods for sulphate quantification and has attempted to determine the threshold level of sulphate likely make these clays vulnerable by lime stabilisation. Clays used in this study were obtained from two different sites in Kochi and contained sulphate in two different concentrations viz., 0.5% and 0.1%. Two different lime percentages were tried out, 3% and 6%. Sulphate content
was varied from 1% to 4% by addition of reagent grade sodium sulphate. The
long term influence of naturally present sulphate is also investigated. X-ray diffraction studies and SEM studies have been undertaken to understand how the soil-lime reactions are affected in the presence of sodium sulphate. Natural sulphate content of 0.1% did not seem to have influenced normal soil lime reactions but 0.5% sulphate could induce significant changes adversely in both compressibility and strength behaviour of lime treated clays after long duration.
Compressibility is seen to increase drastically with increasing sulphate content suggesting formation of ettringite on curing for longer periods. Increase in compression index and decrease in bond strength with curing period underlined the adverse effects induced in lime treated marine clays by the presence of sulphates. Presence of sulphate in concentrations ranging from 0.5 % to 4% is capable of adversely affecting the strength of lime treated marine clays. Considerable decrease is observed with increasing concentrations of sulphate. Ettringite formation due to domination of sodium ions in the system was confirmed in mineralogical studies made. Barium chloride and barium hydroxide is capable of bringing about beneficial changes both in compressibility and strength characteristics of lime treated Cochin marine clays in the presence of varying concentrations of sulphate and is strongly influenced by curing time. Clay containing sodium sulphate has increased strength values when either of barium compounds was used with lime ascompared with specimens treated with lime only. Barium hydroxide is observed to remarkably increase the strength as compared to barium chloride,when used in conjunction with lime to counteract the effect of sulphate.

The constructional activities in the coastal belt of our country often demand deep foundations because of the poor engineering properties and the related problems arising from weak soil at shallow depths.The soil profile in coastal area often consists of very loose sandy soils extending to a depth of 3 to 4 m from the ground level underlain by clayey soils of medium consistency.The very low shearing resistance of the foundation bed causes local as well as punching shear failure.Hence structures built on these soils may suffer from excessive settlements.This type of soil profile is very common in coastal areas of Kerala,especially in Cochin. Further,the high water table and limited depth of the top sandy layer in these areas restrict the depth of foundation thereby further reducing the safe bearing capacity.

Description:

Division of Civil Engineering,Cochin University of Science and Technology

There are numerous parameters affecting the compressibility characteristics of soft
clays. A few of them such as load increment ratio, type of drainage and thickness of
sample were taken up for detailed investigation. However, the main thrust in the
present investigations was to develop an insight into the benefits of preloading
technique, envolve procedures and establish design charts for preparation of a
precompression programme which will substantially reduce the consolidation
settlements of the extremely soft deposits of Cochin marine clays.

The country has witnessed tremendous increase in the vehicle population and increased
axle loading pattern during the last decade, leaving its road network overstressed and
leading to premature failure. The type of deterioration present in the pavement should be
considered for determining whether it has a functional or structural deficiency, so that
appropriate overlay type and design can be developed. Structural failure arises from the
conditions that adversely affect the load carrying capability of the pavement structure.
Inadequate thickness, cracking, distortion and disintegration cause structural deficiency.
Functional deficiency arises when the pavement does not provide a smooth riding surface
and comfort to the user. This can be due to poor surface friction and texture, hydro
planning and splash from wheel path, rutting and excess surface distortion such as
potholes, corrugation, faulting, blow up, settlement, heaves etc. Functional condition
determines the level of service provided by the facility to its users at a particular time and
also the Vehicle Operating Costs (VOC), thus influencing the national economy.
Prediction of the pavement deterioration is helpful to assess the remaining effective
service life (RSL) of the pavement structure on the basis of reduction in performance
levels, and apply various alternative designs and rehabilitation strategies with a long
range funding requirement for pavement preservation. In addition, they can predict the
impact of treatment on the condition of the sections. The infrastructure prediction models
can thus be classified into four groups, namely primary response models, structural
performance models, functional performance models and damage models.
The factors affecting the deterioration of the roads are very complex in nature and vary
from place to place. Hence there is need to have a thorough study of the deterioration
mechanism under varied climatic zones and soil conditions before arriving at a definite
strategy of road improvement. Realizing the need for a detailed study involving all types
of roads in the state with varying traffic and soil conditions, the present study has been
attempted.
This study attempts to identify the parameters that affect the performance of roads and to
develop performance models suitable to Kerala conditions. A critical review of the
various factors that contribute to the pavement performance has been presented based on
the data collected from selected road stretches and also from five corporations of Kerala.
These roads represent the urban conditions as well as National Highways, State Highways
and Major District Roads in the sub urban and rural conditions.
This research work is a pursuit towards a study of the road condition of Kerala with
respect to varying soil, traffic and climatic conditions, periodic performance evaluation of
selected roads of representative types and development of distress prediction models for
roads of Kerala. In order to achieve this aim, the study is focused into 2 parts. The first
part deals with the study of the pavement condition and subgrade soil properties of urban
roads distributed in 5 Corporations of Kerala; namely Thiruvananthapuram, Kollam,
Kochi, Thrissur and Kozhikode. From selected 44 roads, 68 homogeneous sections were
studied. The data collected on the functional and structural condition of the surface
include pavement distress in terms of cracks, potholes, rutting, raveling and pothole
patching. The structural strength of the pavement was measured as rebound deflection
using Benkelman Beam deflection studies. In order to collect the details of the pavement
layers and find out the subgrade soil properties, trial pits were dug and the in-situ field
density was found using the Sand Replacement Method. Laboratory investigations were
carried out to find out the subgrade soil properties, soil classification, Atterberg limits,
Optimum Moisture Content, Field Moisture Content and 4 days soaked CBR. The relative
compaction in the field was also determined. The traffic details were also collected by
conducting traffic volume count survey and axle load survey.
From the data thus collected, the strength of the pavement was calculated which is a
function of the layer coefficient and thickness and is represented as Structural Number
(SN). This was further related to the CBR value of the soil and the Modified Structural
Number (MSN) was found out. The condition of the pavement was represented in terms
of the Pavement Condition Index (PCI) which is a function of the distress of the surface at
the time of the investigation and calculated in the present study using deduct value
method developed by U S Army Corps of Engineers. The influence of subgrade soil type
and pavement condition on the relationship between MSN and rebound deflection was
studied using appropriate plots for predominant types of soil and for classified value of
Pavement Condition Index. The relationship will be helpful for practicing engineers to
design the overlay thickness required for the pavement, without conducting the BBD test.
Regression analysis using SPSS was done with various trials to find out the best fit
relationship between the rebound deflection and CBR, and other soil properties for
Gravel, Sand, Silt & Clay fractions.
The second part of the study deals with periodic performance evaluation of selected road
stretches representing National Highway (NH), State Highway (SH) and Major District
Road (MDR), located in different geographical conditions and with varying traffic. 8
road sections divided into 15 homogeneous sections were selected for the study and 6 sets
of continuous periodic data were collected. The periodic data collected include the
functional and structural condition in terms of distress (pothole, pothole patch, cracks,
rutting and raveling), skid resistance using a portable skid resistance pendulum, surface
unevenness using Bump Integrator, texture depth using sand patch method and rebound
deflection using Benkelman Beam. Baseline data of the study stretches were collected as
one time data. Pavement history was obtained as secondary data. Pavement drainage
characteristics were collected in terms of camber or cross slope using camber board
(slope meter) for the carriage way and shoulders, availability of longitudinal side drain,
presence of valley, terrain condition, soil moisture content, water table data, High Flood
Level, rainfall data, land use and cross slope of the adjoining land. These data were used
for finding out the drainage condition of the study stretches.
Traffic studies were conducted, including classified volume count and axle load studies.
From the field data thus collected, the progression of each parameter was plotted for all
the study roads; and validated for their accuracy. Structural Number (SN) and Modified
Structural Number (MSN) were calculated for the study stretches. Progression of the
deflection, distress, unevenness, skid resistance and macro texture of the study roads were
evaluated. Since the deterioration of the pavement is a complex phenomena contributed
by all the above factors, pavement deterioration models were developed as non linear
regression models, using SPSS with the periodic data collected for all the above road
stretches. General models were developed for cracking progression, raveling progression,
pothole progression and roughness progression using SPSS. A model for construction
quality was also developed.
Calibration of HDM–4 pavement deterioration models for local conditions was done
using the data for Cracking, Raveling, Pothole and Roughness. Validation was done
using the data collected in 2013. The application of HDM-4 to compare different
maintenance and rehabilitation options were studied considering the deterioration
parameters like cracking, pothole and raveling. The alternatives considered for analysis
were base alternative with crack sealing and patching, overlay with 40 mm BC using
ordinary bitumen, overlay with 40 mm BC using Natural Rubber Modified Bitumen and
an overlay of Ultra Thin White Topping. Economic analysis of these options was done
considering the Life Cycle Cost (LCC). The average speed that can be obtained by
applying these options were also compared. The results were in favour of Ultra Thin
White Topping over flexible pavements. Hence, Design Charts were also plotted for
estimation of maximum wheel load stresses for different slab thickness under different
soil conditions. The design charts showed the maximum stress for a particular slab
thickness and different soil conditions incorporating different k values. These charts can
be handy for a design engineer.
Fuzzy rule based models developed for site specific conditions were compared with
regression models developed using SPSS. The Riding Comfort Index (RCI) was
calculated and correlated with unevenness to develop a relationship. Relationships were
developed between Skid Number and Macro Texture of the pavement.
The effort made through this research work will be helpful to highway engineers in
understanding the behaviour of flexible pavements in Kerala conditions and for arriving
at suitable maintenance and rehabilitation strategies.
Key Words: Flexible Pavements – Performance Evaluation – Urban Roads – NH – SH
and other roads – Performance Models – Deflection – Riding Comfort Index – Skid
Resistance – Texture Depth – Unevenness – Ultra Thin White Topping

At this era of energy crisis and resource depletion, availability
of conventional materials throughout the year in quantity and quality,
pose a hectic problem for the builders. Adding fuel to the fire, the
demand of these materials increases day by day, since the housing
and habitat requirements exponentially increase time to time. There is
an international concern over this crisis and researchers are
reorienting themselves, so as to evolve appropriate masonry units,
using locally available cheap materials and technology. The concept
of green material and construction has been well conceived in the
research so that marginal materials and unskilled labour can be
employed for the mass production of building blocks. In this context,
considering earth as a sustainable material, there is a growing interest
in the use of it, as a modern construction material. Solid waste
management is one of the current major environmental concerns in
our country. Our country is left with millions of cubic metre of waste
plastics. One of the methods to satisfactorily address this solid waste
management and the environmental issues is to suitably accommodate
the waste in some form (as fibres). Their employability in block making
in the form of fibres (plastic fibre- mud blocks) can be investigated
through a fundamental research. Also, the review of the existing
literature shows that most studies on natural fibres are focussed on cellulose based/ vegetable fibres obtained from renewable plant
resources except in very few cases, where animal fibre, plastic fibre
and polystyrene fabric were used.
At this context, for the plastic fibre-mud blocks to be more
widely applicable, a systematic quantification of the relevant physical
and mechanical properties of the fibre masonry units is crucial, to
enable an objective evaluation of the composite material’s response to
actual field condition. This research highlights the salient
observations from the detailed investigation of a systematic study on
the effect of embedded fibres, made of plastic wastes on the
performance of stabilised mud blocks.

Soil moisture plays a cardinal role in sustaining eclological balance and
agricultural development – virtually the very existence of life on earth. Because of the
growing shortage of water resources, we have to use the available water most efficiently
by proper management. Better utilization of rainfall or irrigation management depends
largely on the water retention characteristics of the soil.Soil water retention is essential to life and it provides an ongoing supply of water
to plants between periods of irrigation so as to allow their continued growth and
survival.It is essential to maintain readily available water in the soil if crops are to sustain
satisfactory growth. The plant growth may be retarded if the soil moisture is either
deficient or excessive. The optimum moisture content is that moisture which leads to
optimum growth of plant. When watering is done, the amount of water supplied should
be such that the water content is equal to the field capacity that is the water remained in
the saturated soil after gravitational drainage. Water will gradually be utilized
consumptively by plants after the water application, and the soil moisture will start
falling. When the water content in the soil reaches the value known as permanent
wilting point (when the plant starts wilting) fresh dose of irrigation may be done so that
water content is again raised to the field capacity of soil.Soil differ themselves in some or all the properties depending on the difference
in the geotechnical and environmental factors. Soils serve as a reservoir of the nutrients
and water required for crops.Study of soil and its water holding capacity is essential for the efficient
utilization of irrigation water. Hence the identification of the geotechnical parameters
which influence the water retention capacity, chemical properties which influence the
nutrients and the method to improve these properties have vital importance in irrigation
/ agricultural engineering. An attempt in this direction has been made in this study by
conducting the required tests on different types of soil samples collected from various
locations in Trivandrum district Kerala, with and without admixtures like coir pith,
coir pith compost and vermi compost. Evaluation of the results are presented and a
design procedure has been proposed for a better irrigation scheduling and management.

Description:

Division of Civil Engineering, Cochin University of Science and Technology

Wind energy has emerged as a major sustainable source of energy.The efficiency of wind power generation by wind mills has improved a lot during the last three decades.There is still further scope for maximising the conversion of wind energy into mechanical energy.In this context,the wind turbine rotor dynamics has great significance.The present work aims at a comprehensive study of the Horizontal Axis Wind Turbine (HAWT) aerodynamics by numerically solving the fluid dynamic equations with the help of a finite-volume Navier-Stokes CFD solver.As a more general goal,the study aims at providing the capabilities of modern numerical techniques for the complex fluid dynamic problems of HAWT.The main purpose is hence to maximize the physics of power extraction by wind turbines.This research demonstrates the potential of an incompressible Navier-Stokes CFD method for the aerodynamic power performance analysis of horizontal axis wind turbine.The National Renewable Energy Laboratory USA-NREL (Technical Report NREL/Cp-500-28589) had carried out an experimental work aimed at the real time performance prediction of horizontal axis wind turbine.In addition to a comparison between the results reported by NREL made and CFD simulations,comparisons are made for the local flow angle at several stations ahead of the wind turbine blades.The comparison has shown that fairly good predictions can be made for pressure distribution and torque.Subsequently, the wind-field effects on the blade aerodynamics,as well as the blade/tower interaction,were investigated.The selected case corresponded to a 12.5 m/s up-wind HAWT at zero degree of yaw angle and a rotational speed of 25 rpm.The results obtained suggest that the present can cope well with the flows encountered around wind turbines.The areodynamic performance of the turbine and the flow details near and off the turbine blades and tower can be analysed using theses results.The aerodynamic performance of airfoils differs from one another.The performance mainly depends on co-efficient of performnace,co-efficient of lift,co-efficient of drag, velocity of fluid and angle of attack.This study shows that the velocity is not constant for all angles of attack of different airfoils.The performance parameters are calculated analytically and are compared with the standardized performance tests.For different angles of ,the velocity stall is determined for the better performance of a system with respect to velocity.The research addresses the effect of surface roughness factor on the blade surface at various sections.The numerical results were found to be in agreement with the experimental data.A relative advantage of the theoretical aerofoil design method is that it allows many different concepts to be explored economically.Such efforts are generally impractical in wind tunnels because of time and money constraints.Thus, the need for a theoretical aerofoil design method is threefold:first for the design of aerofoil that fall outside the range of applicability of existing calalogs:second,for the design of aerofoil that more exactly match the requirements of the intended application:and third,for the economic exploration of many aerofoil concepts.From the results obtained for the different aerofoils,the velocity is not constant for all angles of attack.The results obtained for the aerofoil mainly depend on angle of attack and velocity.The vortex generator technique was meticulously studies with the formulation of the specification for the right angle shaped vortex generators-VG.The results were validated in accordance with the primary analysis phase.The results were found to be in good agreement with the power curve.The introduction of correct size VGs at appropriate locations over the blades of the selected HAWT was found to increase the power generation by about 4%

Description:

Division of Safety and Fire Engineering,School of Engineering,Cochin University of Science and Technology

Files in this item: 1

The increasing tempo of construction activity the world over creates heavy pressure
on existing land space. The quest for new and competent site often points to the needs
for improving existing sites, which are otherwise deemed unsuitable for adopting
conventional foundations. This is accomplished by ground improvement methods,
which are employed to improve the quality of soil incompetent in their natural state.
Among the construction activities, a well-connected road network is one of the basic
infrastructure requirements, which play a vital role for the fast and comfortable
movement of inter- regional traffic in countries like India.One of the innovative ground improvement techniques practised all over the world is
the use of geosynthetics, which include geotextiles, geomembranes, geogrids, etc .
They offer the advantages such as space saving, enviromnental sensitivity, material
availability, technical superiority, higher cost savings, less construction time, etc .
Because of its fundamental properties, such as tensile strength, filtering and water
permeability, a geotextile inserted between the base material and sub grade can
function as reinforcement, a filter medium, a separation layer and as a drainage
medium. Though polymeric geotextiles are used in abundant quantities, the use of
natural geotextiles (like coir, jute, etc.) has yet to get momentum. This is primarily
due to the lack of research work on natural geotextilcs for ground improvement,
particularly in the areas of un paved roads. Coir geotextiles are best suited for low cost
applications because of its availability at low prices compared to its synthetic
counterparts. The proper utilisation of coir geotextilcs in various applications demands large quantities of the product, which in turn can create a boom in the coir
industry. The present study aims at exploring the possibilities of utilising coir
geotextiles for unpaved roads and embankments.The properties of coir geotextiles used have been evaluated. The properties studied
include mass per unit area, puncture resistance, tensile strength, secant modulus, etc .
The interfacial friction between soils and three types of coir geotextiles used was also
evaluated. It was found that though the parameters evaluated for coir geotextiles have
low values compared to polymeric geotextiles, the former are sufficient for use in
unpaved roads and embankments. The frictional characteristics of coir geotextile - soil
interfaces are extremely good and satisfy the condition set by the International
Geosynthetic Society for varied applications.The performance of coir geotextiles reinforced subgrade was studied by conducting
California Bearing Ratio (CBR) tests. Studies were made with coir geotextiles placed
at different levels and also in multiple layers. The results have shown that the coir
geotextile enhances the subgrade strength. A regression analysis was perfonned and a
mathematical model was developed to predict the CBR of the coir geotextile
reinforced subgrade soil as a function of the soil properties, coir geotextile properties,
and placement depth of reinforcement.The effects of coir geotextiles on bearing capacity were studied by perfonning plate
load tests in a test tan1e This helped to understand the functioning of geotextile as
reinforcement in unpaved roads and embankments. The perfonnance of different
types of coir geotextiles with respect to the placement depth in dry and saturated
conditions was studied. The results revealed that the bearing capacity of coir-reinforced soil is increasing irrespective of the type of coir geotextiles and saturation
condition.The rut behaviour of unreinforced and coir reinforced unpaved road sections were
compared by conducting model static load tests in a test tank and also under repetitive
loads in a wheel track test facility. The results showed that coir geotextiles could
fulfill the functions as reinforcement and as a separator, both under static and
repetitive loads. The rut depth was very much reduced whik placing coir geotextiles
in between sub grade and sub base.In order to study the use of Coir geotextiles in improving the settlement
characteristics, two types of prefabricated COlf geotextile vertical drains were
developed and their time - settlement behaviour were studied. Three different
dispositions were tried. It was found that the coir geotextile drains were very effective
in reducing consolidation time due to radial drainage. The circular drains in triangular
disposition gave maximum beneficial effect.In long run, the degradation of coir geotextile is expected, which results in a soil -
fibre matrix. Hence, studies pertaining to strength and compressibility characteristics
of soil - coir fibre composites were conducted. Experiments were done using coir
fibres having different aspect ratios and in different proportions. The results revealed
that the strength of the soil was increased by 150% to 200% when mixed with 2% of
fibre having approximately 12mm length, at all compaction conditions. Also, the
coefficient of consolidation increased and compression index decreased with the
addition of coir fibre.Typical design charts were prepared for the design of coir geotextile reinforced
unpaved roads. Some illustrative examples are also given. The results demonstrated that a considerable saving in subase / base thickness can he achieved with the use of
eoir geotextiles, which in turn, would save large quantities of natural aggregates.

Description:

Division of Civil Engineering,
Cochin University of Science and Technology

Files in this item: 1

Ushakumary, E R; Dr.Madhu, G(Cochin University Of Science And Technology, April , 2013)

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Abstract:

Heavy metals are major toxic pollutants with severe health effects on
humans. They are released into the environment from a variety of industrial
activities. Cadmium, lead, zinc, chromium and copper are the most toxic
metals of widespread use in industries such as tanning, electroplating,
electronic equipment manufacturing and chemical processing plants. Heavy
metals contribute to a variety of adverse health environmental effects due to
their acute and chronic exposure through air, water and food chain.
Conventional treatment methods of metal removal are often limited by their
cost and ineffectiveness at low concentrations. Adsorption, the use of
inactivated biomass as adsorbents offers an attractive potential alternative to
their conventional methods. Mango peel and Alisma plantago aquatica are
naturally occurring and abundant biomass can offer an economical solution for
metal removal.The Cd(II), Pb(II), Zn(II), Cr(III) and Cu(II) adsorption by milled
adsorbents of mango peel and Alisma plantago aquatica were evaluated in
batches.